- Author: Travis M Bean
Proper weed management is important for several reasons, but in general younger orchards are much more susceptible to the negative impacts of weed overgrowth. The full canopies of mature orchards limit the amount of sunlight reaching the orchard floor, which suppresses the growth of many weed species. Younger trees also have less extensive rooting systems, putting them into direct competition with weeds for water and nutrients. The presence of weeds provides habitat for insects, pathogens, and rodents, which can affect trees of all ages through direct damage to vascular tissue and foliage, and as disease vectors.
Rank growth of weeds also visually obscures irrigation...
- Author: Rebecca Ozeran
Many factors make weed management on federal public lands an interesting challenge.
In September I was invited to join one of the Sierra National Forest Rangeland Management Specialists to explore a medusahead infestation in one of the grazing allotments she manages. The infested meadow used to be a homestead, though the only obvious reminder is the cluster of still-productive apple trees in the middle of an otherwise grass-dominated site. Pines and other conifers border the meadow, and a forest road divides the meadow into two parts. The portion uphill of the road is steeper and has more trees interspersed with the herbaceous vegetation, while the downhill portion is a more expansive, gentler sloping meadow. Due to the...
- Author: Richard Smith
Weed control in lettuce and other crops is a key issue this time of year. Purslane is particularly problematic and is adapted to warm conditions and can grow very rapidly especially during July and August. At times growers and PCA's are disappointed with the efficacy of Kerb on this weed. Kerb is effective in controlling purslane but it is readily leached and, if applied at planting, it can be moved below the zone of germinating weed seeds with the germination water. For instance, 6-8 hours of sprinkler water (1.5 to 2.0 inches) are commonly applied in the first germination water which can move the Kerb below the upper 0.5 inch of soil which is the zone where the weed seeds germinate; the movement of Kerb with the germination water is...
- Author: Richard Smith
Onions is a challenging crop in which to achieve good weed control. They are planted in high density configurations that preclude the effective use of cultivation. Cultural practices such as locating plantings in fields have low weed populations, as well as preirrigating up a flush of weeds followed by killing them with shallow cultivation can be effective in minimizing the population of weeds that emerge during the crop cycle.
In general, excellent weed control for many of the common cool and warm season vegetables can be accomplished by a combination of the registered pre- and post-emergence herbicides. The weed control challenges in onions occur with weeds that are not well controlled by currently registered herbicides. It is...
- Author: Lynn M. Sosnoskie
Field bindweed (Convolvulus arvensis) is a perennial vine native to the Mediterranean region of Europe and Northern Africa that has become naturalized throughout much of the world. The species can reproduce vegetatively (through the spread of rhizomes) and via seed production. Field bindweed seedlings can be distinguished from emerging perennial vines by the presence of two square- to kidney-shaped cotyledons. Leaves are arrow-shaped and alternate along the developing stem. The true leaves of seedlings resemble those on mature vines (just being smaller in size to start). Within six weeks of emergence, the seedlings have developed a taproot and a significant number of lateral roots. For more information about field...
